The invention relates to the field of measuring instruments, and more particularly to a shock-resistant gage housing for a pressure measuring device such as a sphygmomanometer.
Pressure measuring devices such as sphygmomanometers, which are used to measure the arterial blood pressure of a patent, typically include a pneumatic bulb which inflates a pressure chamber of an attached sleeve that is fitted over a limb (i.e., an arm or a leg) of the patient. A diaphragm or bellows assembly, responsive to changes in fluid pressure of the pneumatic bulb and the sleeve pressure chamber, is positioned in a gage housing which is fluidly connected to the pressure chamber of the sleeve through flexible tubes or hoses. A pointer of a dial indicator is interconnected to the bellows assembly through a movement mechanism which is retained within the gage housing, whereby inflation of the bellows causes corresponding circumferential movement of the pointer enabling a blood pressure measurement procedure to be carried out by a caregiver.
Typically, the above referred to movement mechanisms are quite intricate and complex, and are akin in terms of their manufacture and precision to Swiss watches. For example, and in one such movement mechanism, a pair of diaphragm springs are attached adjacent opposing ends of a spindle. A bottom end of the spindle is placed in contact with the bellows assembly and a twisted bronze band perpendicularly disposed at the top end of the spindle is connected in parallel by a horizontally disposed spring bent part. As the spindle deflects axially in response to the inflation of the bellows, the bent spring part is also caused to deflect, thereby causing the and to twist. The pointer, attached to the bronze band, therefore is caused to rotate in relation to an adjacent dial face.
Devices, such as the foregoing, include numerous moving and relatively complex components, some or each of having numerous bearing surfaces. Therefore, such known devices must be manufactured with relatively strict tolerance margins and significant associated costs in terms of both precision and failure rate in order to minimize errors.
In addition, any adjustments required after assembly of the above mechanisms, such as to null the pointer or adjust the sensitivity of the device, require substantial tear down or at least same undesired disassembly.
Furthermore, discrete and separate elements are typically required within the instrument housing for independently supporting the movement mechanism and the bellows assembly, respectively, and for defining an expansion chamber for the bellows assembly there between.
A more recent and simplified movement mechanism is described in U.S. Pat. No. 5,996,829, incorporated by reference in its entirety. The mechanism includes a vertically disposed axial cartridge having a spirally wrapped ribbon spring with one end mounted to an axially movable elongate shaft and the remaining end of the spring being attached to a fixed tubular sleeve. A bottom portion of the elongate shaft is positioned relative to an expandable diaphragm or bellows, wherein subsequent axial translation of the shaft, caused by movement of the diaphragm, elongates the spirally wound ribbon spring and produces repeatable circumferential movement of a pointer supported at the top end of the shaft. The above movement mechanism is far more lightweight than those previously known due to its simplified construction.
A further advance, described in U.S. Pat. No. 6,168,566, also incorporated by reference in its entirety, permits the design of a housing retaining the movement mechanism described in the ""829 patent to be far more compact.
One feature common to the above pressure measuring devices is the need to fluidly interconnect the gage housing which contains the movement mechanism, the dial face and the indicating member with the interior of the inflatable sleeve. This interconnection is typically done using an elongated hose which is connected to a barb on the sleeve at one end and to an inlet port disposed on one end of the gage housing. It is a general object in the field to simplify the manufacture of these devices and to better integrate the design thereof.
It is a primary object of the present invention to overcome the above-noted deficiencies of the prior art.
Therefore and according to a preferred aspect of the invention, there is provided a blood pressure measuring apparatus comprising:
a sleeve having an inflatable interior;
a gage housing including a movement mechanism; and
snap-fitting means for directly attaching said gage housing to said sleeve to permit fluid interconnection between the interior of said inflatable sleeve and the interior of said housing without requiring a hose there between.
Preferably, the snap-fitting means includes at least one socket provided on the sleeve which receives an engagement portion of the gage housing. The socket includes an opening which extends into the interior of the sleeve and the engagement portion of the gage housing includes a corresponding opening which extends into the interior of the gage housing.
The movement mechanism contained within the gage housing can assume literally any form, such as gearless or non-gearless, provided that the movement mechanism is responsive to changes in pressure in the interior of the sleeve.
Therefore, any gage housing having any form of engagement portion which typically receives fluid through a hose can be reconfigured, adapted, or reconfigured so as to permit attachment to the socket of the inflatable sleeve.
An advantage provided by the present invention is that a blood pressure measuring apparatus is provided in which a gage housing can be directly mounted to an inflatable sleeve without requiring any interconnecting hoses between the housing and the sleeve. That is to say, a sealed mechanical interconnection is provided between a gage housing and a sleeve permits fluid pressure changes within the sleeve to be immediately detected by mechanisms provided within the gage housing allowing a blood pressure measurement to be taken more readily than those previously known.
A further advantage is that previously known gage housings can be retrofitted to permit their attachment to the sleeve in a hoseless manner. Adapters can be provided which permit the suitable attachment, the adapters being attachable to the engagement port of the housing. The adapters can further be provided integrally with the engagement port to permit dedicated use with the socket on the sleeve.
These and other objects, features, and advantages will be more readily apparent to one of ordinary skill in the field from the following Detailed Description which should be read in conjunction with the accompanying drawings.